A positive temperature coefficient (PTC) component exhibits a PTC effect that renders the same to be useful as a PTC circuit protection device, such as a fuse. The PTC component includes a PTC polymeric material unit and first and second electrodes formed on two opposite surfaces of the PTC polymeric material unit. The PTC polymer material unit includes a polymer matrix that contains a crystalline region and a non-crystalline region, and a particulate conductive filler that is dispersed in the non-crystalline region of the polymer matrix and that is formed into a continuous conductive path for electrical conduction between the first and second electrodes. The PTC effect is a phenomenon that occurs when the temperature of the polymer matrix is raised to its melting point, in which crystals in the crystalline region start melting, resulting in generation of a new non-crystalline region. As the new non-crystalline region is increased to an extent to merge into the original non-crystalline region, the conductive path of the particulate conductive filler will become discontinuous and the resistance of the PTC polymer material will be sharply increased, thereby resulting in an electrical disconnection between the first and second electrodes.
Referring to FIG. 1, a conventional surface-mounted PTC circuit protection device 1 includes a PTC component 14, a first insulation layer 15, a second insulation layer 16, a first electrode 17 and a second electrode 18. The PTC component 14 includes a first electrically conductive member 12, a second electrically conductive member 13 and a polymeric material layer 11 laminated therebetween. The polymeric material layer 11 exhibits PTC behavior and includes a polymer matrix and a particulate conductive filler dispersed in the polymer matrix.
The first insulation layer 15 is disposed on the first electrically conductive member 12, whereas the second insulation layer 16 is disposed on the second electrically conductive member 13. The first electrode 17 is electrically coupled to the first electrically conductive member 12, and is disposed on the first insulation layer 15 and further extends toward the second insulation layer 16. Likewise, a second electrode 18 is electrically coupled to the second electrically conductive member 13, and is disposed on the second insulation layer 16 and further extends toward the first insulation layer 15.
The conventional surface-mounted PTC circuit protection device is usually installed in an electronic equipment. The PTC circuit protection device may be tripped to its high resistance state when the working current of the electronic equipment reaches the trip current of the PTC circuit protection device. The electronic equipment cannot be used until the PTC circuit protection device is reset or returned to its lower resistance state.